I am in the process of designing a new crane service body for my service truck. I would like to run 4x6 rectangular tubing the length of the frame. i also have to run 4x6 across the complete width of the bed to support the boxes and crane. to keep my bed as close as possible to the frame i am wondering, if it will be as strong to notch the lengthwise pieces 3 inches and notch the cross pieces the same, and fit them together in an interlocking cross? once the sit into each other weld them out completely. would this be a weak spot since i am essentially braking the spine of the tubing or would they be just as strong since i am welding them to the intersecting tubing.Thanks for ya'lls help.